'''
全球60亿人，每人可以分得128亿吨的小麦，而且这才只2的63次方
如果是2的n次方会怎么样
'''

count = 64
sum = 0


def calWheat(i, nowLen):
    global sum
    if nowLen == count:
        return
    if nowLen == 0:
        sum = sum + i
        calWheat(i, nowLen + 1)
    else:
        sum = sum + i * 2
        calWheat(i * 2, nowLen + 1)


def forExpress():
    global sum
    for i in range(count):
        print(i, pow(2, i))
        sum = sum + pow(2, i)


if __name__ == '__main__':
    calWheat(1, 0)
    # forExpress()
    print(sum)
